1. Field of the Invention
The present invention relates to an image forming system and a computer readable medium containing a program.
2. Description of Related Art
There have been known image forming systems including two image forming apparatuses connected in series in the paper conveyance direction. When such image forming systems perform duplex printing, the first image forming apparatus disposed upstream in the paper conveyance direction prints an image on the front side of paper, and the second image forming apparatus disposed downstream in the paper conveyance direction prints an image on the back side the of paper, for example.
Japanese Unexamined Patent Application Publication No. 2005-225123 discloses a tandem continuous-form printer that prints an image on one side of paper with a first printer engine, and prints an image on the other side of the paper with a second printer engine when a duplex printing mode is selected.
Japanese Unexamined Patent Application Publication No. 2005-225123, however, does not disclose or suggest which of the image data corresponding to the front side of paper and the image data corresponding to the back side of the paper is to be printed first in a duplex printing mode. In general, in order to perform duplex printing, an additional mechanism has to be provided to allow paper to wait at a predetermined place, such as at a paper turning-over unit, after an upstream image forming apparatus completes printing on one side of paper and before a downstream image forming apparatus is ready for printing on the other side of the paper. In addition, there is a danger that the paper, whose one side is printed, deforms while staying at the turning-over unit until the downstream image forming apparatus is ready for printing on the other side of the paper.